1. Field of the Invention
This invention relates to an improved method for the transportation of chips of synthetic rubber.
2. Description of the Prior Art
Synthetic rubber such as polybutadiene and butadiene-containing copolymer rubber is used widely as a modifier for making improvements in the impact strength and like properties of resins.
Synthetic rubber is generally available in the form of blocks in bales on the market. For the above-mentioned application, it is a routine practice to chop synthetic rubber blocks into small chips by means of a rubber chopper. Thereafter, the chips are dissolved in a monomer or the like and the resultant solution is then subjected to a polymerization reaction. In the case of high impact polystyrene for example, a butadiene-containing homo- or co-polymer rubber block is chopped into chips by means of a rubber chopper and the chips are then dissolved in a styrene monomer to prepare a rubber solution in the styrene monomer. A high impact polystyrene resin with improved impact strength can then be obtained by polymerizing the rubber solution.
Upon dissolution of synthetic rubber chips in a monomer or the like, the chips of the synthetic rubber which have been discharged from a rubber chopper or the like are usually transported in a continuous operation by air transportation or by a belt conveyor, followed by their addition to a monomer stored in a mixing tank or the like.
Since the synthetic rubber is very sticky, the chips of the synthetic rubber tend to stick on the piping or belt conveyor in the course of their transportation. When the operation is continued without removal of the thus-stuck chips, more and more chips may then be caused to stick so that the operation cannot be continued any longer. Moreover, a great deal of labor and time is required for the removal of the so-stuck synthetic rubber chips.
Various attempts have heretofore been made with a view toward reducing the sticking problem of such synthetic rubber chips in the course of their transportation.
It has been proposed, for example, to add powder such as talc or stearic acid to synthetic rubber chips. Although this method is effective in reducing the sticking of synthetic rubber chips, it is accompanied by a drawback that the powder remains as an impurity in the final product.
It has also been known to mirror-finish a conveyor, piping or the like or to coat it with TEFLON.RTM. (astrade name for polytetrafluoroethylene). In the case of mirror-finishing, its effect is not very remarkable. TEFLON.RTM. coating is certainly effective in reducing the sticking problem but is accompanied with a danger that occurrence of static electricity is induced.